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Search Results: 1 - 10 of 19912 matches for " coronary blood flow "
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Predictive Study of Velocimetry in the Coronary Artery after Iodinated Contrast Agent Injection  [PDF]
Nora Hocine, Julie Colnot, Hélène Masset, Didier Franck
International Journal of Medical Physics,Clinical Engineering and Radiation Oncology (IJMPCERO) , 2017, DOI: 10.4236/ijmpcero.2017.61009
Abstract: This study aims to determine the retention time of iodinated contrast agents (ICA) in the coronary artery. The mechanical aspect of ICA displacement was studied in order to better understand the effect of these products on the inner wall of the artery of patients with coronary artery stenosis, undergoing repeated imaging examinations with iodinated contrast agents. ICA flow, ICA and blood flow in the artery were modelled. The fluid was regarded to be viscous, incompressible and Newtonian. Blood flow was presumed to be unidirectional, laminar and unstationary. Iodine flow velocity and retention time were calculated using the Runge-Kutta 4th order method programmed in C++ and MatLab R2013a language. The results showed that for coronary artery CT-scans, ICA retention time is 1 minute 40 seconds and for coronary arteriography it is between 2.41 and 3.61 seconds. The values calculated were compared to theoretical values and to clinical observations. The results enabled us to validate our model.
Valoración del flujo coronario mediante PET en la población mexicana sin enfermedad arterial coronaria
Alexánderson, Erick;Ricalde, Alejandro;Estradas, José;Alexánderson, E Graciela;Meave, Aloha;
Archivos de cardiología de México , 2005,
Abstract: coronary artery disease (cad) represents the principal cause of morbidity and mortality in our environment. positron emission tomography (pet) is a new technique in our country that allows the assessment of myocardial perfusion and the absolute quantification of the coronary blood flow (cbf) through the utilization of radiotracers using the same criteria employed in conventional nuclear cardiology. cbf normal values have been determined in other populations around the world. no studies in our country assessing in a non-invasive way the cbf have been published before. the quantification of cbf in healthy population is important to establish a standard measure and determine through it, the effects of the many diseases that change the coronary blood flow. the quantification of the cbf, the calculation of coronary blood flow reserve (cfr) and the endothelium dependent vasodilatation index (edvi) through pet is possible performing three different acquisition stages: rest, cold pressor test (cpt) and pharmacologic stress using ammonia as radiotracer. the aim of this study was to evaluate the cbf, the cfr and the edvi in healthy mexican volunteers. results: global basal cbf was 0.34 (±0.09) ml/g/min, during cpt increased to 0.55 (±0.17) ml/g/min and during the stress increased to 1.18 (±0.25). cfr was 3.5 (±0.65) and edvi was 1.55 (±0.33). conclusions: cfr and edvi values obtained in mexican healthy population correlates very well with those reported in the literature. this values represents a reference to further research that use this technology.
Fisiología coronaria y su utilidad para el cardiólogo intervencionista: Medición invasiva de la presión y flujo coronarios
Barrera-Ramírez, Carlos Felipe;Escaned, Javier;
Archivos de cardiología de México , 2005,
Abstract: one of the most important limitations of coronary angiography is the inability to characterize the physiological significance of an intermediate coronary stenosis. measuring coronary blood flow and pressure provides unique information that complements anatomic evaluation and facilitates decision-making in the cardiac catheterization unit. this review discusses the fundamental concepts of coronary physiology, methodology, and clinical applications of coronary and flow measurements.
Treinamento físico de nata??o promove remodelamento cardíaco e melhora a perfus?o sanguínea no músculo cardíaco de SHR via mecanismo dependente de adenosina
Barros, Juliana Gon?alves de;Redondo, Fernanda Roque;Zamo, Fernanda de Souza;Mattos, Katt Cristina;Angelis, Kátia De;Irigoyen, Maria Cláudia;Oliveira, Edilamar Menezes de;
Revista Brasileira de Medicina do Esporte , 2011, DOI: 10.1590/S1517-86922011000300009
Abstract: exercise training (et) has been used as non-pharmacological therapy for hypertension treatment and swimming physical training is recognized for yielding cardiac remodeling in experiments. however, little is known on the effects of adenosine (ado) resulting from et as hypertension prevention and treatment. objective: to evaluate cardiac remodeling and the role of adenosine in cardiac blood flow distribution (bf) to the myocardium after aerobic et on shr. methods: 28 male shr, babies and adults, were submitted to swimming training protocol during 10 weeks (5 times a week - 1 h a day). colored micro spheres protocols were used to evaluate blood flow, morphological techniques were used to evaluate cardiac hypertrophy and biochemical analysis were performed to verify enzyme activity in the adenosine formation. results: et attenuated the evolution of hypertension in the shr babies group (s: 145 2; t: 140 2mmhg), hr was lower in adult shr (s: 340 4; t: 321 6bpm) and ch increased in both groups (tb: 12%; ta: 10%). at basal condition, bf was increased in trained babies (s: 4.745 ± 2.145; t: 6.970 ± 2.374mi/heart) and higher vasodilatation response was observed due to adenosine infusion (s: 18.946 ± 6.685; t: 25.045 ± 7.031mi/heart). in this group, the et promoted a higher 5'-nucleotidase enzyme activity leading to a higher adenosine formation (s: 0.45 ± 0.09; t: 1.01 ± 0.05). conclusion: the swimming training developed ch as well as increased adenosine formation, leading to higher coronary blood flow, and its important role in hypertension regulation was demonstrated.
Thrombolytic therapy of acute myocardial infarction
D.P. Sementsov
Rational Pharmacotherapy in Cardiology , 2007,
Abstract: Importance of thrombolytic therapy for restoration of coronary blood flow in acute myocardial infarction is emphasized. Indications and contraindications, advantages and disadvantages for thrombolysis therapy are discussed. The ways of different thrombolytics implementation, efficacy criteria and possible side effects are also presented.
Effect of left ventricular systolic dysfunction on cerebral hemodynamics in patients with acute myocardial infarction (the results of observational studies).
V.E. Kulikov,M.Je. Hapman,P.A. Barov,M.A. Toneeva
Rational Pharmacotherapy in Cardiology , 2012,
Abstract: Aim. To study the effect of left ventricular (LV) systolic dysfunction on cerebral hemodynamic in patients with ST segment elevation myocardial infarction (STEMI) during acute period.Material and methods. Cerebral hemodynamics ultrasound assessment was performed in the extra-and intracranial vessels in 118 patients with STEMI.Results. Significant changes in cerebral hemodynamics were found in LV systolic dysfunction with ejection fraction (LVEF) ≤40% due to hemispheric blood flow asymmetry in the middle cerebral artery (MCA) as large as 45.1±6.7% with correlation coefficient r=-0.87. Compensation of cerebral blood flow was manifested in vasoconstriction or vasodilation (resistive index 0.63-0.76 and 0.49-0.43 units, respectively).Conclusion. A strong relationship between LV systolic dysfunction and cerebral hemodynamic was found in patients with STEMI. It was manifested in significant contralateral hemispheric blood flow asymmetry in MCA in patients with LVEF ≤40%. Reduction in cerebral blood flow velocity activated autoregulation mechanism in the form of vasoconstriction or vasodilation.
Comparison between Diastolic Subendocardial Tissue Pressures Measured Directly or Calculated from Pressure-Flow Relations  [PDF]
Jacques R. Rouleau, Bernard Cantin, John G. Kingma Jr
World Journal of Cardiovascular Diseases (WJCD) , 2017, DOI: 10.4236/wjcd.2017.77020
Abstract: Changes in intramyocardial tissue pressure modulate the relationship between coronary pressure and flow during the cardiac cycle. The present study compared the relation between measured and calculated diastolic subendocardial tissue pressure and coronary pressure at zero flow in anesthetized dogs after modulation of either coronary sinus (i.e. Fogarty catheter) or left ventricular intracavity (i.e. volume loading) pressure. Experiments were conducted in anesthetized, instrumented dogs; coronary pressure flow relations were constructed during pharmacologic vasodilatation and intramyocardial tissue pressure was measured using micromanometer pressure sensors. Elevated coronary sinus pressures did not affect subendocardial pressure-flow relations signifying that diastolic tissue pressure within this layer is the effective coronary back pressure. Higher left ventricular intracavity pressure did not affect either diastolic subendocardial tissue pressure or pressure flow relations within this layer. Results show a direct linear relation (y = 1.106x - 0.652; r2 = 0.59. P = 0.001) between measured and calculated diastolic subendocardial tissue pressure and coronary pressure at zero-flow over a wide range of pressures after either LV systemic or coronary sinus pressure modulation. Knowledge of back pressure in the subendocardium is useful for the evaluation of efficacy of cardiac interventions on myocardial perfusion particularly at the level of the microcirculation.
Gender differences in response to cold pressor test assessed with velocity-encoded cardiovascular magnetic resonance of the coronary sinus
Pierre-Julien Moro, Antonin Flavian, Alexis Jacquier, Frank Kober, Jacques Quilici, Bénédicte Gaborit, Jean-Louis Bonnet, Guy Moulin, Patrick J Cozzone, Monique Bernard
Journal of Cardiovascular Magnetic Resonance , 2011, DOI: 10.1186/1532-429x-13-54
Abstract: Twenty-four healthy volunteers (12 men, 12 women) underwent CMR in a 3 Tesla MR imager. Coronary sinus flow was measured at rest and during CPT using non breath-hold velocity encoded phase contrast cine-CMR. Myocardial function and morphology were acquired using a cine steady-state free precession sequence.At baseline, mean MBF was 0.63 ± 0.23 mL·g-1·min-1 in men and 0.79 ± 0.21 mL·g-1·min-1 in women. During CPT, the rate pressure product in men significantly increased by 49 ± 36% (p < 0.0001) and in women by 52 ± 22% (p < 0.0001). MBF increased significantly in both men and women by 0.22 ± 0.19 mL·g-1·min-1 (p = 0.0022) and by 0.73 ± 0.43 mL·g-1·min-1 (p = 0.0001), respectively. The increase in MBF was significantly higher in women than in men (p = 0.0012).CMR coronary sinus flow quantification for measuring myocardial blood flow revealed a higher response of MBF to CPT in women than in men. This finding may reflect gender differences in endothelial-dependent vasodilatation in these young subjects. This non invasive rest/stress protocol may become helpful to study endothelial function in normal physiology and in physiopathology.Endothelial dysfunction (ED) is a key element in the development of atherosclerosis and represents one of the earliest manifestations of coronary artery disease [1]. Gender-specific differences in cardiovascular risk have been evidenced by several modalities in human subjects and in animals, and gender-related differences in vascular vasomotion have been documented [2-6]. Differences in the epidemiology of coronary artery disease (CAD) between women and men remain largely unexplained as we are still unable to explain why women are protected towards CAD until older age compared with men [7]. Current evidence supports the role of endothelium in these differences. In particular, the cardiovascular protection in pre-menopausal women is mainly attributed to an enhanced vasodilative capacity of the endothelium [3,4]. Myocardial blood flow (MBF) in
Importance of the TIMI frame count: implications for future trials
Mark A Appleby, Andrew D Michaels, Michael Chen, C Gibson Michael
Trials , 2000, DOI: 10.1186/cvm-1-1-031
Abstract: The TIMI (Thrombolysis in Myocardial Infarction) flow grade is a widely used method for the assessment of coronary artery flow in acute coronary syndromes. Flow in coronary arteries is classified as grade 0 (no flow), grade 1 (penetration without perfusion), grade 2 (partial perfusion) or grade 3 (complete perfusion). TIMI grade 3 flow requires that antegrade flow distally be as rapid as antegrade flow proximally. The PAMI (Primary Angioplasty in Myocardial Infarction) investigators have redefined TIMI grade 3 flow as opacification of the vessel within three cardiac cycles (ie 'PAMI' grade 3 flow) [1]. This new definition increases the number of arteries that are considered to have normal flow by about 10% over the original definition of TIMI grade 3 flow, requiring adjustment of analyses comparing original and redefined TIMI grade 3 flows [2].The TIMI flow method for defining coronary artery flow has proven useful in assessing reperfusion strategies over the past 15 years. However, a number of limitations have become apparent. TIMI flow grade assessment is limited by interobserver variability (core laboratories agree 71% of the time) [3] and by the need for a more objective quantification of the different degrees of complete perfusion in a coronary artery. In order to overcome these problems, the TIMI frame count was developed as a more quantitative index of coronary artery flow [4].In the CTFC method, the number of frames required for dye to reach a standardized distal landmark is counted. A correction factor is required to compensate for the longer length of the left anterior descending artery (LAD) compared with the circumflex and right coronary arteries (the number of frames required for dye to traverse the LAD is divided by 1.7). The frame count number after adjustment for vessel length is given the term 'corrected TIMI frame count' [4].The first frame taken for measurements is the frame in which dye touches both borders of the coronary artery and moves forwar
Differential effects of androgens on coronary blood flow regulation and arteriolar diameter in intact and castrated swine
Erin K O'Connor, Jan R Ivey, Douglas K Bowles
Biology of Sex Differences , 2012, DOI: 10.1186/2042-6410-3-10
Abstract: Pigs received intracoronary infusions of physiologic levels (1–100 nM) of testosterone, the metabolite 5α-dihydrotestosterone, and the epimer epitestosterone while left anterior descending coronary blood flow and mean arterial pressure were continuously monitored. Following sacrifice, coronary arterioles were isolated, cannulated, and exposed to physiologic concentrations (1–100 nM) of testosterone, 5α-dihydrotestosterone, and epitestosterone. To evaluate effects of the androgen receptor on acute androgen dilation responses, real-time PCR and immunohistochemistry for androgen receptor were performed on conduit and resistance coronary vessels.In vivo, testosterone and 5α-dihydrotestosterone produced greater increases in coronary conductance in the intact compared to the castrated males. In vitro, percent maximal dilation of microvessels was similar between intact and castrated males for testosterone and 5α-dihydrotestosterone. In both studies epitestosterone produced significant increases in conductance and microvessel diameter from baseline in the intact males. Androgen receptor mRNA expression and immunohistochemical staining were similar in intact and castrated males.Acute coronary vascular responses to exogenous androgen administration are increased by endogenous testosterone, an effect unrelated to changes in androgen receptor expression.
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